A composite material is a mixture. It has played a great role in many fields, replacing many traditional materials. Composite materials are divided into metal and metal composite materials, non-metal and metal composite materials, and non-metal and non-metal composite materials according to their composition. According to its structural characteristics, it is divided into: ① fiber reinforced composite materials. It is composed of various fiber reinforcements placed in the matrix material. Such as fiber reinforced plastics, fiber reinforced metals, etc. ② sandwich composite material. It is composed of surface materials and core materials with different properties. Usually the face material has high strength and thinness; the core material is light and low in strength, but has a certain stiffness and thickness. It is divided into two types: solid interlayer and honeycomb interlayer. ③ fine-grained composite materials. The hard fine particles are evenly distributed in the matrix, such as dispersion-strengthened alloys, cermets, etc. ④ Hybrid composite materials. It consists of two or more reinforcing phase materials mixed in one matrix phase material. Compared with ordinary single-reinforced phase composites, its impact strength, fatigue strength and fracture toughness are significantly improved, and it has special thermal expansion properties. It is divided into intralayer hybrid, interlayer hybrid, sandwich hybrid, intralayer/interlayer hybrid and super-hybrid composite.